Why are we still under a drought?

Over the past week, much of Mid-Missouri received significant rainfall totals. Enough to put us slightly over the average total rainfall for the month of March. Despite the rainfall, all of Mid-Missouri is still under a drought.

There is a reason why we are still lacking in moisture even though we met the total average March rainfall. The reason has to do with the many layers of the soil.

There are several layers of soil, and each layer of soil holds its own specific purpose and is made of different components. This directly affects the absorptivity of each soil layer. This means that each layer absorbs water (or lets water pass through) at different rates.

The first layer of soil is the topsoil. Generally, the topsoil can absorb rainfall accumulation rather quickly, depending on the dryness of the soil. The drier the soil, the denser the soil is, making it more difficult for the soil to initially absorb rainfall. This is why if it downpours in Arizona they will experience a flash flood even though the Amazon rainforest receives more rainfall in a single day than Arizona, but flooding is not an issue.

When the topsoil is able to absorb water, it can only hold so much as it takes time for the water to travel further in the ground due to denser subsoils. So when rain is falling faster than the water can travel down into the earth, this is what leads to runoff and potential flooding. When this happens, it does not help mitigate flooding for an area under a drought.

For example, and area may receive a solid 1/2″ of accumulation, but it all came quickly within a few hours. This is when the accumulation turns into runoff because the rain is falling faster than the ground to absorb. An area may receive the target amount of accumulation that could get them out of a drought, but unless that rain comes gradually over time allowing that rain to absorb into the ground, lots of rain will not help rid an area of a drought.

Normal 0 false false false EN-US X-NONE X-NONE /* Style Definitions */ table.MsoNormalTable{mso-style-name:”Table Normal”;mso-tstyle-rowband-size:0;mso-tstyle-colband-size:0;mso-style-noshow:yes;mso-style-priority:99;mso-style-parent:””;mso-padding-alt:0in 5.4pt 0in 5.4pt;mso-para-margin-top:0in;mso-para-margin-right:0in;mso-para-margin-bottom:10.0pt;mso-para-margin-left:0in;line-height:115%;mso-pagination:widow-orphan;font-size:11.0pt;font-family:”Calibri”,”sans-serif”;mso-ascii-font-family:Calibri;mso-ascii-theme-font:minor-latin;mso-hansi-font-family:Calibri;mso-hansi-theme-font:minor-latin;}